Devices for controlling the valves of internal combustion engines

ABSTRACT

A device for controlling the valves of an internal combustion engine having overhead valves comprises a control cam, and two oscillating rockers for each valve. The free end of each rocker is disposed between the cam and the end of the valve stem. The free end of the rocker in contact with the cam has a roller which is in rolling contact with the cam. The lower planar surface of this rocker is in contact with the spherical head portion at the free end of the other rocker. This spherical free end is in in turn in contact with the end or tappet of the valve stem. The rocker in contact with the end of the valve stem oscillates in a plane perpendicular to the axis of the valve. The rocker in contact with the cam oscillates about an axis parallel to the axis of the camshaft. The mid-point of the path of contact between the spherical head portion and the end of the valve stem is disposed substantially along the axis of the valve.

United States Patent Gordini DEVICES FOR CONTROLLING THE VALVES OFINTERNAL COMBUSTION ENGINES Inventor: Amedee France S.A. GordiniAutomobiles, Viry- Chatillon (Essone), France Filed: Jan. 14, 1971 Appl.No.: 106,390

Gordini, Viry-Chatillon,

Assignee:

Foreign Application Priority Data Jan. 15, 1970 France ..7001376 U.S.Cl. ..123/90.27, 123/9039, 123/90.41 Int. Cl. ..F0ll 1/04, F011 l/l 8Field of Search ..123/90.27, 90.39, 90.41

References Cited UNITED STATES PATENTS Apfelbeck ..l23/90.27 Fuchs..123/90.27

[ 1 Mar. 27, 1973 FOREIGN PATENTS OR APPLICATIONS 920,484 3/1963 GreatBritain ..l23/90 A Primary ExaminerAl Lawrence Smith Attorney-Stevens,Davis, Miller & Mosher {57] ABSTRACT A device for controlling the valvesof an internal combustion engine having overhead valves comprises acontrol cam, and two oscillating rockers for each valve. The free end ofeach rocker is disposed between the cam and the end of the valve stem.The

free end of the rocker in contact with the cam has a roller which is inrolling contact with the cam. The lower planar surface of this rocker isin contact with the spherical head portion at the free end of the otherrocker. This spherical free end is in in turn in contact with the end ortappet of the valve stem. The rocker in contact with the end of thevalve stem oscillates in a plane perpendicular to the axis of the valve.The rocker in contact with the cam oscillates about an axis parallel tothe axis of the camshaft. The mid-point of the path of contact betweenthe spherical head portion and the end of the valve stem is disposedsubstantially along the axis of the valve.

4 Claims, 5 Drawing Figures PATENTEDHARZYIHYS SHEET 3 OF 5 Q4 3 Mms B. 82 T].

5 2 6mm 8 0 w H v 1 J I 6 G. 1 w 0 3 PATEHIEUmznm SHEET 5 OF 5 DEVICESFOR CONTROLLING THE VALVES OF INTERNAL COMBUSTION ENGINES The presentinvention concerns a control device for valves for internal combustionengines, in particular for so-called radial valve type engines.

These types of engines whose combustion chambers are in the form ofhemispherical heads and whose valve axes are disposed along radii of thehemispherical head, permit by this arrangement a maximum valve surfacewhich enables high performances, the interest for these engines being incompetition.

Nonetheless, these engines have only had until now a limited success incompetition. In fact, the radial orientation of the valves therefore indiflerent directions does not satisfactorily enable their control by acamshaft as the axis of the valve is not located in the plane of thecam. The control forces of the valves are not transmitted axially whichresults in the rapid wear and the jamming or seizing which give thesemotors a reputation of being fragile and lacking endurance.

Known devices for transmitting forces by asupport finger in an annularmember or by desmodromic pivoting control levers do not yield asatisfactory solution to this problem. The large amount of frictionproduced causes rapid heating and wear to the detriment of the precisionof the timing of the valves and the endurance of the motor.

An object of the present invention is a device for controlling valveswhich provides a solution to this problem. This device essentiallycomprises the interposition, between the control cam and the end portionof the stem of the valve, the free ends of two rockers oscillating abouta pivot at their other end, the free end of said first rocker being incontact with the'cam, oscillating in a plane perpendicular to the axisof this cam and being in contact with a spherical head portion of thesecond rocker which is in contact with the end of the stem of the valveand oscillates in the plane of the axis of the valve, the mid-point ofbearing contact of the spherical head portion on the end portion of thisvalve stem being disposed substantially along the axis of the valve. 1

The rocker or lever in contact with the cam is provided with a rollerrolling along this cam, and the plane of the lower surface supported onthe spherical head of the second rocker passes through the axis ofoscillation of said lever, this axis being parallel to the axis of thecamshaft. I

The rocker or lever in contact with the spherical head portionoscillates about an axis situated in a plane perpendicular to the axisof the valve corresponding to the mid-point of the plane of the valvehead.

The plane passing through the axis of symmetry of the cam perpendicularto the camshaft cuts the axis of the valve at a point correspondingsubstantially to the center of the spherical head portion of the supportrocker on the valve.

The end of the valve stem is provided with a connecting end portion of aknown type formed of a wear-resistant alloy whose thickness is adjustedto assure the clearance and thereby the correct timing of the valve.

The group of pivots of the rockers of each cylinder are mounted on acommon connecting member independently centered on the cylinder head forexample on the bore or socket for receiving the spark plug.

Such a device provides the advantage of the transmission of the movementfrom the cams to the valves with a minimum of friction, inherentlooseness, and non-axial forces. The cam surfaces rest on followers inperfect rolling contact. The spherical head portion of the second rockeraxially transmits the thrust of the cam. Its oscillating movementeffects a combined rolling and sliding movement of the spherical headportion. This movement produces a superficial glossing of the contactsurfaces which remain quite small in the order of several squaremillimeters. This results in practically no wear, a great precision ofthe transmission movements, a high mechanical efficiency and a greatendurance.

Another advantage of the device is its simplicity of construction in theform of a separate sub-assembly which can be easily and quickly mountedand dismounted for adjusting and checking, this advantage being veryimportant in competition. It also easily and inexpensively enables theprovision of this type of valve gear to engines not originally providedtherewith.

A preferred embodiment of a device according to the invention is setforth in the description hereinbelow and in the accompanying drawings.It corresponds to valve gear including four valves and a pair ofcamshafts for a hemispherical combustion chamber with a central sparkplug. One camshaft controls two inlet valves ar-v ranged side by side,the other camshaft controls two exhaust valves also arranged side byside but opposite the inlet valves.

In thedrawings:

FIG. 1 shows a view partially in section of the device taken along theline ll of FIG. 2 which includes the axis of the spark plug and twodiametrically opposed valves;

FIG. 2 shows a top plan view of the device without the camshafts;

FIG. 3 shows an elevation view showing a camshaft, the rockers and thevalves in their relative positions;

F IG. 4 shows a side view showing the mounting of the camshafts, therockers and the valve heads;

FIG. 5 shows perspective view in phantom lines of a cylinder head andits combustion chamber equipped according to the embodiment describedaccording to the invention.

In FIG. 1 the cams 3 and 4 of the camshafts l and 2 partially shown bearagainst the rollers 5 and 6 mounted on the free ends of the rockers 7and 8 whose other ends arepivotally mounted about the pins 9 and 10fixed to a central connecting member 1 1.

The lower surfaces 12 and 13 of the rockers 7 and 8 come to bear againstthe spherical heads portions 14 and 15 of the rockers l6 and 17 whichare also pivotally mounted about the pins 18 and 19 fixed to the member11. Weight-reducing holes 20 and 21 can be provided in the sphericalhead portions 14 and 15 in order to diminish the inertia of thecombination and to facilitate the mounting for machining.

The spherical head portions 14 and 15 also bear on the connecting endportions 22 and 23 covering the heads of the valves 24 and 25. Thevalves slide in the guide bushings 26 and 27 and are seated againsttheir seats 28 and 29 according to a known arrangement by the play orfree motion between two springs 30 and 31 and the annular members 32 and33.

The connecting member 11 for pivoting the rockers 8, 9 and 16, 17 isadjusted on the cylinder head 34 of the motor by centering circularshoulders 35 at the opening of the bore or socket for receiving thespark plug 36. This bore as well as the screw-threaded hole 37 formounting the spark plug are aligned along the axis of the cylinder. Thethreaded hole 37 for the spark plug opensinto the center of thehemispherical head 39 delimiting the combustion chamber 40 with thesurface of the piston head (FIG.

FIG. 2 shows the star-arrangement of the four rockers 16, 16, 17, 17'which correspond to the four valves about the spark plug bore or socket36, their pivot axes 18, 18', l9, 19' on the member 11 and the rockers7-8 and 7 8 disposed two by two in opposed relationship.

FIG. 3 shows the mounting of the bearings 42 for the camshaft 1 on thecylinder head 34 by means of bolts 43. The camshaft 1 is driven by achain-driven gear wheel 44 at its end. A casing 41 covers the entiredevice.

In operation the rotation of the cams 3, 3', 4, 4' rolling along thefollowers 5, 5', 6, 6 causes the oscillation of the rockers 7, 7', 8, 8,situated in the same plane as the cams, about pivots perpendicular tothis plane. The planes of the lower surface 12, 12', 13, 13'

of the rockers extend along the axes of oscillation 9, 9',

10, and come into sliding and rolling support against the spherical headportions 14, 14', 15, 15 0f the rockers 16, 16', 17, 17 which in turnoscillate about axes 18, l8, 19, 19'. The spherical head portions restin rolling and sliding contact on the connecting end portions of tappets22, 22', 23, 23 which cover the ends of the stems of the valves 24, 24,25, 25', the midpoint of the path of bearing contact corresponding tothe axis of the valve.

The combination of the rolling and sliding movement of the sphericalhead portion brings about a rapid glossing or glazing action along thecontact surfaces and a very great resistance to the wear of thesesurfaces. These surfaces are linear on the surfaces 12, 12', 13, 13', ofthe rockers and circular owing to the rotations of the valves on the endportions and are of the order of several square millimeters.

The pivots for the rockers are mounted on the common connecting member11 in the form of a premounted and -adjusted sub-assembly. The member 11is not subject to any particular stress or strain and can beeconomically formed as a cast iron body. The device is economical whichaccrues from its ease of assembly and adjustment.

I claim:

1. A device for controlling the valves of an internal combustion engineof the type having overhead camshafts, comprising:

a first and second rocker for each valve,

each of said rockers being disposed between a control cam on a camshaftand the end portion of the stern of the valve;

the free end of said first rocker being in contact with the control cam;oscillating in a plane perpendicular of the axis of this cam and beingin contact with a spherical head portion on the second of said rockers,

said second rocker being in contact with the end portion of the valvestem and oscillating in a plane containing the axis of the valve, themid-point of the bearing contact of the spherical head portion on theend portion of the valve stem being disposed substantially along theaxis of the valve; and a connecting member for supporting pivots forsaid rockers is centered on the cylinder head by-an opening thereinwhich is substantially coaxial with the spark plug bore of the cylinder.2. A device according to claim 1, wherein said first and second rockersare fitted on oscillation pins in a common connecting member which isconnected to the cylinder head of the engine.

3. A device for controlling the valves of an internal combustion engineof the type having overhead camshafts, comprising:

a first and second rocker arm for each valve,

each rocker mounted for oscillation on a pin at one of ends, the freeends of said rockers being disposed between a control cam on a camshaftand the end portion of the stem of a valve,

the free end of said first rocker having a roller in contact with thecontrol cam, said first rocker being oriented for oscillationin a planeperpendicular of the axis of the control cam, said second rockercomprising a spherical head portion which is in contact with the endportion of the valve stem, and oriented for oscillation in a planecontaining the axis of the valve, the bearing contact surface of thespherical head portion with the end of the valve stem being centered onthe axis of the valve, and I a connecting member for supporting pivotsfor said rockers, said connecting member being centered on the cylinderhead by an opening therein which is substantially coaxial with the sparkplug bore of the cylinder.

4. A device for controlling the valves of an internal combustion engineof the type having overhead Camshafts, comprising:

a first and second rocker arm for each valve,

each rocker mounted for oscillation on a pinat one of itsends, the freeends of said rockers being disposed between a control cam on a camshaftand the end portion of the stern of a valve,

the free end of said first rocker having a roller in contact with thecontrol cam and a bearing surface for contacting the second rocker, saidbearing surface comprising a plane surface disposed beneath said rollerand extending along the axis of the oscillation pin of said firstrocker, said first rocker being oriented for oscillation in a planeperpendicular to the axis of the control cam,

and said second rocker is oriented for oscillation in a plane containingthe axis of the valve, and comprises an integral spherical head portionwhich is in contact with the end portion of the valve stemand centeredon the axis of the valve, and is also in contact with the bearingsurface of said first rocker, and control cam, and first rocker being ina plane which substantially passes through the center of said sphericalhead portion of the second rocker.

1. A device for controlling the valves of an internal combustion engineof the type having overhead camshafts, comprising: a first and secondrocker for each valve, each of said rockers being disposed between acontrol cam on a camshaft and the end portion of the stem of the valve;the free end of said first rocker being in contact with the control cam;oscillating in a plane perpendicular of the axis of this cam and beingin contact with a spherical head portion on the second of said rockers,said second rocker being in contact with the end portion of the valvestem and oscillating in a plane containing the axis of the valve, themid-point of the bearing contact of the spherical head portion on theend portion of the valve stem being disposed substantially along theaxis of the valve; and a connecting member for supporting pivots forsaid rockers is centered on the cylinder head by an opening thereinwhich is substantially coaxial with the spark plug bore of the cylinder.2. A device according to claim 1, wherein said first and second rockersare fitted on oscillation pins in a common connecting member which isconnected to the cylinder head of the engine.
 3. A device forcontrolling the valves of an internal combustion engine of the typehaving overhead camshafts, comprising: a first and second rocker arm fOreach valve, each rocker mounted for oscillation on a pin at one of itsends, the free ends of said rockers being disposed between a control camon a camshaft and the end portion of the stem of a valve, the free endof said first rocker having a roller in contact with the control cam,said first rocker being oriented for oscillation in a planeperpendicular of the axis of the control cam, said second rockercomprising a spherical head portion which is in contact with the endportion of the valve stem, and oriented for oscillation in a planecontaining the axis of the valve, the bearing contact surface of thespherical head portion with the end of the valve stem being centered onthe axis of the valve, and a connecting member for supporting pivots forsaid rockers, said connecting member being centered on the cylinder headby an opening therein which is substantially coaxial with the spark plugbore of the cylinder.
 4. A device for controlling the valves of aninternal combustion engine of the type having overhead camshafts,comprising: a first and second rocker arm for each valve, each rockermounted for oscillation on a pin at one of its ends, the free ends ofsaid rockers being disposed between a control cam on a camshaft and theend portion of the stem of a valve, the free end of said first rockerhaving a roller in contact with the control cam and a bearing surfacefor contacting the second rocker, said bearing surface comprising aplane surface disposed beneath said roller and extending along the axisof the oscillation pin of said first rocker, said first rocker beingoriented for oscillation in a plane perpendicular to the axis of thecontrol cam, and said second rocker is oriented for oscillation in aplane containing the axis of the valve, and comprises an integralspherical head portion which is in contact with the end portion of thevalve stem and centered on the axis of the valve, and is also in contactwith the bearing surface of said first rocker, and control cam, andfirst rocker being in a plane which substantially passes through thecenter of said spherical head portion of the second rocker.